To realize the practical potential of narrow GNRs, methods for
their mass production are sorely needed.
Lithographic patterning has been used to produce wide ribbons (\(>\) 20nm) from
graphene sheets, but the width and smoothness of the GNRs were
limited by the resolution of the lithography and etching techniques. [1]}, [2]}
Bulk amounts of wide (20\(-\) 300nm) and few-layered GNRs were
synthesized by a chemical vapor deposition method.[3]}
Very recently,
two research groups found ways to unroll carbon nanotubes to produce
nanoribbons. Jiao et al. [4]} showed an approach to making GNRs
with smooth edges and a
narrow width distribution (10\(-\) 20 nm) by unzipping
multiwalled carbon nanotubes (MWCNT) through plasma etching of nanotubes partly
embedded in a polymer film, but the ability of mass production through
this method is limited.
On the other hand,
Kosynkin et al. [5]} described a simple solution-based oxidative process
for producing a nearly 100% yield of water soluble nanoribbon structures by
lengthwise cutting and unravelling of MWCNT
side walls. The resulting ribbons are wider (around 100\(-\) 500
nm), and not semiconducting, but easier to make
in large amounts. Multilayered GNRs with a width about 100 nm were produced by
lithium intercalation and exfoliation of carbon nanotubes. [6]}
The above experimental efforts indicate that a large scale production of
narrow GNRs is still very challenging.
